[synchronize releases] Provide parameter to set TargetCommitish field of github release

[lobtx]

TargetCommitish is set to master and cannot be configured through a parameter.

[lobtx]

configuration example:

<execution> <!-- mvn yupiik-tools:synchronize-github-releases@metrics-scraper -Psynchronize-github-releases -->
                <id>metrics-scraper</id>
                <phase>initialize</phase>
                <goals>
                  <goal>synchronize-github-releases</goal>
                </goals>
                <configuration>
                  <!-- required configuration -->
                  <githubRepository>yupiik/metrics-scraper</githubRepository>
                  <tagPattern>{artifactId}-{version}</tagPattern>
                  <targetCommitish>main</targetCommitish>
                  <artifacts>
                    <artifact>
                      <groupId>io.yupiik.metrics</groupId>
                      <artifactId>metrics-scraper</artifactId>
                      <artifacts>
                        <artifact>
                          <type>pom</type>
                          <classifier/>
                        </artifact>
                        <artifact>
                          <type>pom.asc</type>
                          <classifier/>
                        </artifact>
                      </artifacts>
                    </artifact>
                  </artifacts>
                </configuration>
              </execution>

[rmannibucau]

@lobtx I assume it is rare enough to have main AND master so maybe just test if both branches exist on the repo and drop the config?

[lobtx]

Ok that's right, so I check if main exists, if not => master

[lobtx]

@rmannibucau or @fpapon review please ? :)